Altering mileage on odometer

strother · 06-14-2005, 03:45 AM

The original speedometer in my '82 SC only goes to 85 mph. I'm going to buy a used replacement odometer and stick it in, and I want to alter the mileage on the used odometer to match to true miles on the car.

Is it possible to alter the mileage? How does one do it? I promise I am not seeking this information for a malicious purpose.

dean · 06-14-2005, 04:33 AM

You take the speedo apart and manually set the odo to read whatever you want. I think a speedo Co. would do it for you if you are not comfortable. You could practice on your old one if you decide to do it yourself.

Dean

strother · 06-14-2005, 05:00 AM

I'm reasonably comfortable taking something apart and putting it back together. Has anyone here done this before? Any special tools needed? Where is it on the 1-10 difficulty scale?

dean · 06-14-2005, 05:12 AM

I have never done it on a 911. It isn't that hard to do. Just don't touch the numbers or the needles with your fingers.

Dean

Mysterytrain · 06-14-2005, 05:13 AM

Not to highjack this thread..but maybe one of you guys with speedo experience could answer this. Are there two stepper motors inside the speedo ( 78) one for the speedometer and one for the odometer??

RickM · RickM's Garage

Of the few odometers I've seen in the past each would require a visible breach in order to reclock. Is Porsche different?

djmcmath · 06-14-2005, 05:34 AM

Is there any question about resellability? Not to question your integrity, but some buyers may be a little leery of a car with a new odometer without an external verification of the mileage. (shrug) Just a thought.

Dan

strother · 06-14-2005, 05:52 AM

Dan, that's a good point. I was going to document the change by digitally videoing the switch and reclocking, but I'm not sure how to get better verification. From my recollection of Texas's registration process, there isn't a process for disclosing a new odometer. (There is only a process for disclosing whether the odometer reading is inaccurate, I think.)

Rick, I don't mind there being a visible breach in order to reclock -- unless you're talking about something cosmetically unappealing like a broken bezel or something. Does anyone have any input on this?

RickM · RickM's Garage

The "damage" would only be visible if one took the unit apart. It appeared to me that these mechanisms were put together like a puzzle. Each piece was interconnected in a way that any disassembly would expose tampering.

Personally, I'd have a shop do it. They'd probably make the change transparent or provide some type of certificate.

john walker's workshop · 06-14-2005, 07:03 AM

shops won't do it for obvious reasons. find one that is closer to your actual mileage, and keep a record of the exchange as well as the old speedo.

Kurt B · 06-14-2005, 07:07 AM

Take off the face of the speedo, and on the back write the date and what you set the mileage to. I had to have my 84 speedo fixed (gear broke), and later, when I took it apart to clear coat it (which works wonder for faded faces), I noticed that the shop had done this. Makes sense.

Joe Bob · Joe Bob's Garage

Most speedo shops will put a tag in the driver door well next to the VIN sticker with the mileage note.

Zeke · 06-14-2005, 07:46 AM

What Mike said. Have a reputable shop do this one. The documantation is a good idea too. I would use a non digital medium, i.e., a disposable camera.

strother · 06-14-2005, 07:56 AM

I found a semi-retired speedo man. He told me it would be about the same price to have him put a new VDO face on my odometer and recalibrate it. That way, you don't have to mess with the mileage.

He is a funny guy. When I told him it was a 911, he said, "Your odometer broke." I replied, "No. I've avoided that by not pressing in the ..." He cut me off, knowing what I was going to say, and stated, "That is a farce. You can press the trip counter in 8 times a second driving 100 mph and you won't break the odometer. I've been working on German car gauges for 40 years. They just give out."

Kurt B · 06-14-2005, 08:18 AM

That is a farce. You can press the trip counter in 8 times a second driving 100 mph and you won't break the odometer. I've been working on German car gauges for 40 years. They just give out

HAHAHa...glad I know this now. Somewhere along the line, someone pressed it while driving and either then or later, it broke. Thus the odometer adjust while driving legend began!

hoosierdaddy · 06-14-2005, 08:38 AM

Strother
Check with your DMV about this issue because in some states I don't think you are allowed to alter an odometer at all , you simply document your actual mileage and the starting mileage on the new head unit . If you decide to do this on your own just keep it to yourself and hopefully for the next owner you set the correct mileage on the new head unit .

strother · 06-14-2005, 09:46 AM

Here's a link to a good thread about replacing a broken gear in an SC/Carrera speedometer: Odometer Gear replacement for Electronic Speedometers (long)

It has lots of good pictures of the guts of the speedometer. Looks like you could easily adjust the odometer once you cracked open the case.

MAS · MAS's Garage

How about biting the bullet... and going for a (high-priced) oil change at the local Porsche dealer before you swap the speedo/odo. Then they'll have the old milage with date on the service records.

-MAS

strother · 06-14-2005, 11:03 AM

Quote:

Originally posted by MAS
How about biting the bullet... and going for a (high-priced) oil change at the local Porsche dealer before you swap the speedo/odo. Then they'll have the old milage with date on the service records.

-MAS

That's a good idea, but I think I've decided to have the speedometer man simply replace the face and recalibrate it. Then, no problem, because the odometer will remain untouched.

Formerly Steve Wilkinson · 06-14-2005, 12:07 PM

North Hollywood Speedo set my '83 SC odo back to 000000 with no muss, no fuss, no questions asked. (I totally rebuilt the car, every moving piece, and asked them to do it when they recalibrated the speedo for larger tires.) I don't plan to ever sell the car, since I have three times as much money in it as it's worth, so the false reading is irrelevant. (What will I do rather than selling it? Give it to my daughter, give it to a friend, give it to a museum...)

If you want to do it yourself, you carefully pry off the bezel that holds the glass in place, behind the big black surruound that shows on the front of the dashboard. It's very easy to do with a small knife, taking careful little bites. I've done it.

You replace it my tapping and pressing it back into place. The fact that the speedo has been opened by an amateur will be perfectly obvious to anybody with a pulse, since the professionals replace the bezel with some kind of rotating tool that leaves an absolutely smooth surface. I suspect that half the mid-year and older 911 speedos out there have been opened--take a look at yours--either to illegally turn the odometer back or to legally replace the odo drive gear after somebody tried to zero the odometer with the car in motion.

Stephan